feat: Add an is_registered global value to indicate whether the exten…

…sion has been loaded (#83)

* feat: Add an is_registered global value to indicate whether the extension has been loaded

* fix format

* unregister magics after each test

bigquery_magics/__init__.py

@@ -18,6 +18,9 @@
 context = bigquery_magics.config.context
 __version__ = bigquery_magics.version.__version__
 
+# Whether the magics has already been reigstered by some other packages.
+is_registered = False
+
 
 def load_ipython_extension(ipython):
     """Called by IPython when this module is loaded as an IPython extension."""
@@ -29,11 +32,21 @@ def load_ipython_extension(ipython):
     )
     ipython.register_magic_function(_cell_magic, magic_kind="cell", magic_name="bqsql")
 
+    global is_registered
+    is_registered = True
+
+
+def unload_ipython_extension(ipython):
+    global is_registered
+    is_registered = False
+
 
 __all__ = (
     # For backwards compatibility we need to make the context available in
     # the path google.cloud.bigquery.magics.context.
     "context",
     "__version__",
     "load_ipython_extension",
+    "unload_ipython_extension",
+    "is_registered",
 )

tests/unit/test_bigquery.py

@@ -74,6 +74,8 @@ def ipython_interactive(request, ipython):
     with ipython.builtin_trap:
         yield ipython
 
+        ipython.get_ipython().extension_manager.unload_extension("bigquery_magics")
+
 
 @pytest.fixture()
 def ipython_ns_cleanup():
@@ -2138,3 +2140,16 @@ def test_bigquery_magic_bigframes_with_dry_run__should_fail():
 
     with bf_patch, pytest.raises(ValueError):
         ip.run_cell_magic("bigquery", "--dry_run", sql)
+
+
+@pytest.mark.usefixtures("ipython_interactive")
+def test_test_bigquery_magic__extension_not_loaded__is_registered_set_to_false():
+    assert bigquery_magics.is_registered is False
+
+
+@pytest.mark.usefixtures("ipython_interactive")
+def test_test_bigquery_magic__extension_loaded__is_registered_set_to_true():
+    ip = IPython.get_ipython()
+    ip.extension_manager.load_extension("bigquery_magics")
+
+    assert bigquery_magics.is_registered is True